Dry Ice Is the Newest Weapon Against Rats

Rats have taken over cities around the globe, but there's a certain mystique to a New York rat. Remarkable generalists when it comes to diet, rats in New York generally eat whatever they can find and live wherever there's space. Keeping them out of homes is a perpetual concern.

Now, New York and other cities are turning to a new weapon to fight this ancient war: dry ice. In March, New York City began filling rat burrows with dry ice in order to kill rats. Outside of a container, the dry ice turns to gaseous carbon dioxide, suffocating the rodents.

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“Or, nicely put, they go to sleep and they don’t wake up,” said the city's Director of Pest Control Ricky Simeone at the time.

As anyone who has dealt with a rat problem can attest, one problem with traditional rat eliminators is getting the rats to march to their own destruction. The animals often have an uncanny ability to ignore traps. Dominating the planet doesn't come easily, and if it were easy to pick off rats they'd be long gone by this point. Despite years of attacking the problem, pest control company Orkin ranks New York has having the second-worst rat problem in the country.

In one 2017 demonstration, dry ice was able to kill 1,2000 rats in a single park. However, when New York Mayor Bill de Blasio watched a dry ice extermination today, but it didn't go as planned: a rat escaped.

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Another NYCHA worked tried to kill it with a shovel. But the rat got away 2/2

Speaking at a press conference afterwards in Brooklyn, Caroline Bragdon, the director of neighborhood interventions for pest control at the city's health department, wanted to make clear that dry ice isn't a silver bullet.

"Typically, you would do multiple insertions over time. The dry ice is inserted into the rat burrow where rats are living. Then you would cover the burrow as dry ice evaporates, they're asphyxiated and they die. You may have to go back for a series of applications. Rats escape, you may have to go back at a later time, come back tomorrow."

By placing the dry ice underground, it keeps the dead rat bodies underground as well, decomposing and eventually becoming part of the soil.

Dry ice, first produced in 1835 by French inventor Adrien-Jean-Pierre Thilorier, has had a winding road to becoming a rat killer. Cities including Boston and Washington, D.C. have been seeking approval for dry ice since 2016. They were stopped by the EPA, which oversees enforcement of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).

FIFRA doesn't recognize dry ice (which is frozen carbon dioxide) as a rodenticide and the agency demanded the cities halt their usage. But as warm summers and food waste have kept rat problems at the forefront of city living, the EPA has relented. It's allowed Bell Laboratories to develop Rat Ice, which the company advertises as "the only approved usage of dry ice for rodents in the U.S."

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